Water-based air-conditioning unit cools air without compressors

Researchers have developed a water-based air-conditioning system that cools air to as low as 18°C without energy-intensive compressors and chemical refrigerants.

Led by Associate Professor Ernest Chua from the Department of Mechanical Engineering at the National University of Singapore’s (NUS) Faculty of Engineering, the team’s air-conditioning system is claimed to be a cost-effective and sustainable solution to regulating ambient air conditions.

Chua said, “For buildings located in the tropics, more than 40 per cent of the building’s energy consumption is attributed to air-conditioning. We expect this rate to increase dramatically, adding an extra punch to global warming.”

According to NUS, the system consumes about 40 per cent less electricity than current compressor-based air-conditioners and negates the use of chemical refrigerants including chlorofluorocarbon and hydrochlorofluorocarbon for cooling. The system also generates drinking water while it cools ambient air.

Chua said, “First invented by Willis Carrier in 1902, vapour compression air-conditioning is the most widely used air-conditioning technology today. This approach is very energy-intensive and environmentally harmful. In contrast, our novel membrane and water-based cooling technology is very eco-friendly – it can provide cool and dry air without using a compressor and chemical refrigerants. This is a new starting point for the next generation of air-conditioners, and our technology has immense potential to disrupt how air-conditioning has traditionally been provided.”

Current air-conditioning systems require a large amount of energy to remove moisture and to cool the dehumidified air. By developing two systems to perform these two processes separately, the NUS Engineering team believe they can better control each process and achieve greater energy efficiency.

The new system first uses an innovative membrane technology to remove moisture from humid outdoor air. The dehumidified air is then cooled via a dew-point cooling system that uses water as the cooling medium instead of chemical refrigerants.

Unlike vapour compression air-conditioners, the system does not release hot air to the environment. Instead, a cool air stream that is comparatively less humid than environmental humidity is discharged – negating the effect of micro-climate. About 12 to 15 litres of drinking water can also be harvested after operating the air-conditioning system for a day.

“Our cooling technology can be easily tailored for all types of weather conditions, from humid climate in the tropics to arid climate in the deserts. While it can be used for indoor living and commercial spaces, it can also be easily scaled up to provide air-conditioning for clusters of buildings in an energy-efficient manner. This novel technology is also highly suitable for confined spaces,” said Chua.

The research team is currently refining the design of the air-conditioning system to further improve its user-friendliness. The NUS researchers are also working to incorporate features including pre-programmed thermal settings based on human occupancy and real-time tracking of its energy efficiency. The team hopes to work with industry partners to commercialise the technology.

Looks to be a very interesting development for tropical climes. In the more affluent areas over cooling of buildings is common while elsewhere little cooling can be afforded and the working environment is unpleasant. It will be interesting to see how this competes with absorption chilling which is not applied enough.

I would not recommend drinking the water from any ductwork condensate system unless it was sterilised.

Good news, but how about a description of the device from an engineering perspective? Where’s the detail Engineers would like to know? What is the membrane made of? What mechanisms are used to transfer heat? Is there a descriptive diagram?

I see this new cycle as a complete boon, no boondoggle here at all. Other forms of “dew point” cooling have been worked before, but this appears to be an improvement in that no water consumption at all was mentioned, rather that water (limited quantity) is produced, depending on the water mass in air in intake air. The water could be utilized for other than drinking, but drinking is OK, after bacteria removal, rest assured. System must be maintained in a highly clean state, otherwise nasty mold will result…don’t drink that.

This alternative technology is sure to make waves as A/C will become a necessity in many areas.
Kudos to the team who have thought alternatively to the conventional process. Congrats to the NUS engineering team

I’ve often thought why these big luxury boats don’t fix pipes to the hulls to transfer the temperature of the surrounding sea, which is always going to be less than the air temp, into water in the pipes & then into cooling rads to cool the state rooms.

Barry F’s comment is a fine example of lateral thinking: and even value Engineering.
Looking at the contribution from and effect on the complete ‘system’ is surely what Engineers do naturally (no pun intended, come to think of it, why not!) because the influences of all factors are relevant. Could it be that ship design is still not fully integrated? Or do the designers of swanky yachts have to take too much notice of the aesthetic wishes of the owners: who can afford to buy their way out of anything that upsets them?

Using the sea water to cool the vessel would make sense if the cost of designing, building and maintaining a salt-water-resistant heat exchange system was reasonable; I suspect the research is active (the materials used to build all those bit-barns being dropped into cold waters by big tech) and soon people will better understand which materials can work and which can’t.

At the end of the day it’s about the cost of implementing what we already have versus implementing a new design. the new design has to be technologically disruptive while affording zero compromise to existiing design considerations

Ahh thank you this is actually incredibly useful! The thing is I’m looking for an A/C unit for the office I run (basically the temperature is so up and down that we basically NEED one to just keep things acclimatised). It’s not a huge office perse but it’s also not huge. I also really don’t want to get a measly little thing that doesn’t make any difference, I’d rather just invest in a solid product. So I was wondering really what people’s preferred A/C unit is? Or if not that, which one their office uses and if it’s good or bad or not? Also where is the best place to buy A/C units? (I literally have no clue), I came across this retailer which is near to the office, has anyone used them or heard of them before? (this is them: http://www.easyairconditioning.com/). I am surprisingly (or not) not exactly an air conditioning expert so any advice or recommendations would be much appreciated!

I fitted a DeLonghi ‘click-clack’ split air con system in my front room 14 years ago and it is still going strong with almost no maintenance. I have a ducted one in my bedroom and this works fine but is much noisier than the split one. If you want to fit it yourself I would recommend one that comes with pre-gassed pipes or you will need to invest in vacuum pumps and gauges (or get it fitted professionally). Although it seems my Delonghi is no longer available I see that you can get ones with a similar ‘quick or ‘easy’ coupling system – look carefully at instructions though as some called quick – still need careful fitting of flared copper pipe connectors and a bleeding regime to get the air out. The simplest seem to be the ones with an integral connector that connects both the ‘to’ and ‘from’ pipes from the indoor unit to the external pump – no expertise needed. They come with a fixed length of pipes so you need to mount the external unit on the wall (or Ground) within a few feet of the indoor unit – they seem to be available for about 500-600 pounds. The ducted ones use a 4″or 5″ flexible pipe that can you just dangle out of the window so are the simplest to fit but quite noisy.

That is a very goid idea however to remove heat you have to create a temperature lower then that which you need to remove so I don’t think water of itself absorb that amount of heat per second.
Please feel free to contact me I am working on something we might can work together.

Step # 1 (in the tropics) should always be put the reflective stuff in the roof / ceiling.
Neighbours just did that with their new house – when you walk in there in the afternoon it feels like someone has left the a/c running – zero power consumption. That and a floor fan, & you are quite comfortable!